Auto trans shift points

[RenoHuskerDu]

Hi m8s,

This is a side thread to http://www.aulro.com/afvb/showthread...17#post1578717, in which we discussed auto trans shift points being a factor in td5 NVH (noise, vibration, harshness).


My shift points seem to be about what others describe. I shot a little video of light throttle acceleration MD002931.AVI - YouTube. In it you can see

• upshift 2nd at 25kmph
• upshift 3rd at 38kmph
• upshift 4th at 61kmph
• TC lockup at 89kmph

What if anything can I do to lower shift points? At light throttle they are reasonable but at moderate throttle the shift points are too high imho. It seems like a waste of fuel. By 1900 rpm torque seems to be sufficient for an upshift.

This video is at full throttle from rest MD002932 - YouTube. Again, spinning the motor up so high seems like a waste of fuel. Top speed of 140kmph in the vehicle is achieved at 3500 rpm, so that seems like more a logical shift point than 4200 rpm.

Is there a vendor whose product will modify shift points? I was hoping for that from my performance chip but not sure that I saw any change. I put the chip in the first week I had the vehicle so don't recall clearly how it shifted before.

----------
Reno, Alsace, France
Where the women are pretty, and the men are, well, eh, also pretty
2000 sky blue D2 td5 auto, formerly used in french Fosters Beer adverts

[mturri]

Compushift!

Rgds
Matt

[OffTrack]

I've posted a video capture of the Nanocom One PC interface while accelerating with a fairly light throttle - around 28-30% throttle.

The refresh rate on the PC Interface is pretty slow - it looks like about 3-5 seconds between updates, so precision measurement isn't going to happen.

I've calculated road speed from the transmission output rpm.

Solenoid 1 and 2 indicate the active gear. 1st = Sol 1 off, Sol 2 on, 2nd = Sol 1 on, Sol 2 on, 3rd = Sol 1 on, Sol 2 off, 4th = Sol 1 off, Sol 2 off.

About all this proves is that the Nanocom One PC interface is of marginal use for check upshifts.

The best I can determine in this way is:

2nd: somewhere between 23 and 32 km/h
3rd: " " 40 and 46.5 km/h
4th: " " 56 and 60 km/h

[ame=http://www.youtube.com/watch?v=ATtUt-e0unA]Discovery 2 TD5 Auto upshifts - YouTube[/ame]

cheers
Paul

[RenoHuskerDu]

Compushift! ...

Oops! This link appears to be broken.

[OffTrack]

Oops! This link appears to be broken.

Works here.

The manufacturers site is here:

https://www.hgmelectronics.com/display/hgm/Home

[RenoHuskerDu]

We had the opportunity today to visit a mountain farm restaurant for a quaint local french tradition known as pig day. We ate home-grown pork in several formats, and a good time was had by all but not by our family van (or the pigs).

The clutch cable on our Pug Boxer decided to snap just when we got up there. I managed to get it turned around on the 1-track dirt hill and pointed back down with no clutch to use (it's useful sometimes being a 4-wheeling nut). I limped all the way home in 2nd and came back with the Disco. The moral here is when in doubt, drive the 4x4.

On the way back up that hill I used low range and saw moderate-throttle shift points over 3000rpm. I'd like to tell you light-throttle upshifts too, but they never happen, at least not until you step harder on the pedal. The auto stubbornly hangs onto each gear, whether going uphill, level, or downhill. WTF?

This is going to drive me nuts when trials season starts up next year and I start doing some group runs in the Disco. The shift points in low range must come down. Any tips?

I'm thinking that one easy trick would be to disconnect whatever sender on the TCase there is that indicates it's in low range. But then that might leave the ACE in operation ... in rough terrain where I need axle articulation...

[RenoHuskerDu]

Works here.

The manufacturers site is here:

https://www.hgmelectronics.com/display/hgm/Home

That works, thanks. Yanks, eh.

Do we have forum members running it, happy campers? US$1000 is a lot of money.

[OffTrack]

Hi Reno,

You really need to check for fault codes on the D2 auto box ECU, you'll be working blind otherwise.

It almost sounds as though you have the box in manual mode, although it wouldn't upshift at all if that was the case.

cheers
Paul

[RenoHuskerDu]

Hi Reno,
You really need to check for fault codes on the D2 auto box ECU, you'll be working blind otherwise.[...]

I'm bringing this thread back up as I have new information.

Last month I serviced the trans and pulled codes. There was only one code and it was about a poor connection. The good news was that the ATF coming out looked great, no metal dust in there, and we saw signs that somebody had recently had the trans out.

Given the 270k km on the vehicle, and the very good condition of the trans, it looks like a new one was installed by the LR dealer before I bought the vehicle. That's one less major repair bill to plan for. We replaced the filter then refilled it with synthetic ATF. Shifting is now fine, but the shift points remain too high for my taste.

Towing a heavy trailer today, I had to pull hard up a hill from stop in order to merge with traffic. Imagine my surprise when the torque converter locked up in 2nd gear! I did not know that this trans would do that. It sure will help prevent heat buildup while towing.

I wonder I could wire up something that makes the converter lock up when I push a button? But then in an earlier thread Tombie said

Torque Converter lock-up WILL remain unchanged though - it is hard coded in the TCU

[Fluids]

Hey Reno ... I have heard people say that the TC will lockup in 2nd gear but I have never been able to make it happen ... maybe the extra weight on the back and the higher engine torque, and the uphill grade is what's needed, because I could never get it locked due to speed/engine revs (on a flat road).

If I remember correctly, the spec' for the ZF box says lockup for 3rd & 4th. No mention of 2nd.

Yes, a "manual overide" button would be choice